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51.
Objective To study the altered radiobiological effect of simulative intensity-modulated radiotherapy (SIMR) in cultured human nasopharyngeal carcinoma (NPC) cells and the related mechanism. Methods Single cell suspension of exponentially growing CNE-2 cells, a poor differentiated NPC cell line, was seeded and cultured for 12 hours, then the cells were irradiated in two different models by 6 MV X-ray beams at 3 Gy/min. In single fraction irradiation (SFR) model, cells were irradiated a single fraction of 0, 2, 4, 6 or 8 Gy within 0 to 3 minutes. In S1MR model, cells were irradiated 0, 2, 4, 6 or 8 Gy in 5 frac-tions with interval of 8.0-8.5 minutes between. Clonogenic assay was performed to determine the radiosen-sitivity. Cellular apoptosis was measured by flow cytometry. RT-PCR was used to detect mRNA expressions of Bax and Bcl-2, Respectively. Results Compared with SFR group, the survival fraction in SIMR group was higher at all the dose levels. The values of α, β, D0 and Dq were higher in SIMR group than in SFR group. At dose levels of 2 Gy, 4 Gy and 6 Gy, The early and late apoptotic cells in SIMR group were lower than in SFR group (21.20%: 15.89%, F=18.51, P=0.020;13.00%: 10.20, F=15.67, P=0.040).The mRNA expression of Bax was upregulated in a dose-dependent manner in the both groups. Compared with SFR group, the mRNA expression of Bax in SIMR group was lower at all the dose levels (Mean value of 76.75% : 62.50%, F =36.57, P =0.000). Bcl-2 mRNA expression at every dose level had no significant difference between the two groups (Mean value of 29.25% : 29.75%, F=0.74, P=0.800). Conclusions Prolonged delivery time in SIMR model can decrease the radiobiological effects. 相似文献
52.
单次静注爱肌松(0.3mg·kg-1,对照组)于3.17±0.81分钟(x±s)可获得满意的气管插管条件。预注组(10例)首次量0.27mg·kg-1于预注剂量(0.03mg·kg-1)后5分钟给予,可使爱肌松的起效时间缩短至0.93±0.17分钟(P<0.001),TOF无反应期、25%和90%恢复时间两组无显著差别(P>0.25)。全部病例均获得了良好的气管插管条件,预注的优点还在于能评估患者对所选用非去极化肌松药的敏感性。预往后TOF肌电图T1抑制>10%较无明显TOF抑制者肌松恢复时间显著延长(P<0.05)。同时发现吸入安氟醚可使爱肌松作用时效延长。 相似文献
53.
为确定放射性碘在甲状腺内滞留模式,观察甲状腺吸收放射性碘后的生物效应,进而评价其辐射危害。方法利用活体测量方法,直接测量两个不同年龄组大鼠甲状腺内131Ⅰ的代谢参数。对测量数据进行处理后得到了大鼠甲状腺内131Ⅰ的滞留函数为三指数项函数。结果利用所得三指数项滞留函数的准确方法进行剂量估算,所得的两组动物的甲状腺平均累积吸收剂量分别为7.7Gy和11.5Gy,而一般方法算得的大鼠甲状腺的平均累积吸收剂量比用准确方法高估了66%~91%。结论由于准确方法考虑到影响估算甲状腺所受剂量的一些因素,故可相对准确地反映了131Ⅰ所致不同年龄大鼠甲状腺的吸收剂量。 相似文献
54.
55.
两种剂量奥曲肽治疗食管及胃曲张静脉出血效果比较 总被引:1,自引:1,他引:0
①目的 比较两种剂量奥曲肽治疗食管、胃曲张静脉出血的临床效果。②方法 将 88例食管、胃曲张静脉出血病人随机分为奥曲肽 5 0 μg/h和 2 5 μg/h剂量组 ,观察平均止血时间、止血率、再出血率和不良反应。 ③结果 5 0 μg/h组平均止血时间明显短于 2 5 μg/h组 (t=2 .2 4 ,P <0 .0 5 ) ,总止血率明显高于 2 5 μg/h组 (χ2 =5 .36 0 ,P <0 .0 5 ) ,再出血率较 2 5 μg/h组低 (χ2 =7.990 ,P <0 .0 5 )。两组均有 1例病人出现恶心。④结论 奥曲肽 5 0 μg/h剂量治疗食管、胃曲张静脉出血的效果优于 2 5 μg/h剂量 相似文献
56.
57.
为获得我食品和膳食中放放射性核素含量并为制定?食品中放射性物质限制浓度标准?提供依据,在1982~1086年问由30个辐射防护单位协作,测定了我过14类(27种)特定食品种22种放射性核素浓度.按我国三种主要膳食食类型.从14个正常本底辐射的省或自治区及三个非正常地区采集样品进行分析测定.估算了这些地区居氏15种放射往核素的年摄人最及所致待积剂量毒量.我国正常本底辐射地区成年男子对这15种核索年总摄入量约为4.2×104Bq,所致总待积剂量当量约为0.43×104Sv.在两个天然放射性较高地区天然放射性核素的年摄入量和所致待积剂量当量比正常本底辐射地区高得多,而在该核工厂周围地区采集的食未明显放射性污染.文章还讨论了各类食品或放射性核素对总待积剂量当量的相对贡献. 相似文献
58.
The apparent concentration-effect relationship is the ensemble of many effector units (such as individual cells or channels)
that do not always exhibit a uniform stimulus-effect relationship. This concept is substantiated by many observations of heterogeneity
in receptor-effector populations including hormone secreting cells, response to hormonal stimuli, activity pattern of second
messengers, stimulus-evoked synaptic currents, and single ion channels. The relationship between drug concentration and magnitude
of pharmacologic response is commonly described by the sigmoidalE
max model which was derived from the Hill equation. The sigmoidicity factor (N) in this model is assumed to be a pure mathematical parameter without physiological connotations. This work demonstrates
that the numerical value ofN (measured empirically) is the product of two factors: (i) the degree of heterogeneity of the effector subunits, i.e., the
elemental component that upon drug stimulus contributes its pharmacological effect independently and does not interact with
other subunits (it could range from a single receptor up to a whole tissue), and (ii) value ofN
*—the shape factor of the subunits' concentration-effect relationship. A special case of this approach occurs whenN
*>5, which is an on-off case. HereN is determined by the distribution (density equation) of the subunit values. In case of heterogeneity of the microparameters
of the effector subunits the apparentN will always have a lower value thanN
*. According to this theory it can be concluded that without knowledge of the distribution of the microparameters no mechanistic
interpretation can be deduced from the apparentN value. If in the futureN
* can be determined by theoretical or experimental methods, the distribution function relatingN
* toN can be calculated. The relevance of this theory is increased in view of the progress being made in advanced research techniques
which may enable us to determine the concentration-effect relationship at the level of the individual effector unit. 相似文献
59.
Heather J. Zar Michael J. Asmus Eugene G. Weinberg 《Pediatric allergy and immunology》2002,13(3):217-222
Inhaled therapy using a metered‐dose inhaler (MDI) with attached spacer has been increasingly recognized as the optimal method for delivering asthma medication for acute attacks and chronic prophylaxis. However, in developing countries the cost and availability of commercially produced spacers limit the use of MDI‐spacer delivery systems. A 500‐ml plastic bottle has been recently adapted to function as a spacer. This article reviews the current data on the efficacy of this bottle‐spacer and discusses its advantages and limitations. It is concluded that a modified 500‐ml plastic bottle is an effective spacer; modification and use of this device should be incorporated into international guidelines for the management of children with asthma. 相似文献
60.
Cell culture-based influenza vaccine manufacturing is of growing importance. Depending on virus strains, differences in infection dynamics, virus-induced apoptosis, cell lysis and virus yields are observed. Comparatively little is known concerning details of virus–host cell interaction on a cellular level and virus spreading in a population of cells in bioreactors. In this study, the infection of MDCK cells with different influenza A virus strains in lab-scale microcarrier culture was investigated by flow cytometry. Together with the infection status of cells, virus-induced apoptosis was monitored. A mathematical model has been formulated to describe changes in the concentration of uninfected and infected adherent cells, dynamics of virus particle release (infectious virions, hemagglutinin content), and the time course of the percentage composition of the cell population. 相似文献